A head-up display device that is mountable in a vehicle such as an automobile, and projects a video onto a windshield (a partial reflecting unit) having an inner surface on which a metallic thin film, a dielectric multi-layer film, or the like is formed so that the video is displayed in the field of view through the windshield as a virtual image is also already known in Patent Document 1.
Patent Document 2 discloses a display device in which, for example, a video (a three-dimensional (3D) tire video) projected from a display body configured with a liquid crystal display (LCD) device installed in a dashboard is projected onto a holographic combiner attached to a part (a lower side portion) of a windshield as a vehicle display device that shows a wheel which a driver is directly unable to see through the windshield in a pseudo manner.
Further, as a navigation device that guides a route, a device that projects necessary guidance information (for example, an arrow or the like) onto a windshield of an automobile, and thus the guidance information is displayed for a driver simply and accurately without requiring detailed map data or the like is also already known in Patent Document 3.